This invention relates to a method for assisting an excavator operator with the loading of a mobile transportation implement, in particular a heavy-duty truck, by means of the excavator shovel.
In opencast mines with discontinuous mining, the heavy-duty truck (HD truck) represents a suitable transportation implement, in order to transport the overburden layers and the raw material layers away from the mining site to the raw material processing site or deposit. Depending on the structure of the opencast mine, very long distances possibly must be covered for this purpose. In this case, the driving time of the HD truck is very long as compared to its loading time, which is why it is desirable to load the HD truck as precisely as possible to the maximum permissible payload, in order to keep the operating costs of the opencast mine as low as possible and the productivity as high as possible.
In opencast mines with discontinuous mining, either cable excavators or hydraulic excavators are used as loading tool for HD trucks. Both types of machine serve to pick up the material to be removed by means of a shovel or a bucket and convey it into the loading trough of the HD truck. The task of the excavator operator substantially consists in filling the excavator shovel to the optimum excavator payload by suitable control of the machine and in conveying this payload into the trough of the HD truck with one excavator loading cycle. An excavator loading cycle includes filling of the excavator shovel, moving the shovel over the loading area of the HD truck, unloading into the trough of the HD truck and returning the excavator shovel to the digging site. Corresponding to the maximum payload of the HD truck the excavator operator must repeat several excavator loading cycles, in order to completely load the HD truck. To precisely reach the maximum permissible payload of the HD truck, the excavator operator must perform the last necessary excavator loading cycle such that the excavator shovel only is filled exactly such that the target payload of the HD truck is reached.
Furthermore, the excavator operator must perform unloading of the excavator shovel into the trough of the HD truck such that the material is uniformly distributed in the trough. Especially in the case of very coarse, unbroken material individual pieces of rock can non-uniformly form the resultant load in the trough, which can lead to a strong lateral, front- or rear-side inclination of the HD truck. The excavator operator must actively counteract this effect by targeted unloading of the excavator payload. An uneven load distribution on the loading area of the HD truck during the driving operation can lead to the following disadvantages:                unstable driving behavior/safety hazard for the operator due to tipping hazard of the HD truck        overload of mechanical components (frame, supporting joints, axles, tires) and consequently premature fatigue or rupture        extension of the calculated transport time due to overloading of the HD truck, influence on further HD trucks (jam).        
With respect to the described excavator/HD truck loading cycle, the productivity and the operating costs of the opencast mine substantially depend on the following features:                duration of the excavator loading cycle        degree of utilization of the excavator (ratio of effectively reached payload of the excavator and its maximum permissible payload should be as close as possible to 1)        degree of utilization of the HD truck (ratio of effectively reached working mass of the HD truck and its maximum permissible working mass should be as close as possible to 1)        number of excavator loading cycles which are necessary to completely load the HD truck        necessary maintenance intervals and associated maintenance costs of the machines—by correct load distribution of the payload on the trough of the HD truck, the wear of components such as supporting joints and tires can be reduced decisively. Hence, maintenance costs can be reduced and the availability of the HD trucks can be increased.        
The excavator operator hence can decisively influence the productivity and the operating costs of the opencast mine. Without technical aids, he must rely on his experience in the operation of the excavator and in the assessment of the loading state of the HD truck. In particular, the excavator operator must know the target payload of the HD truck and assess the load distribution of the payload on the trough of the HD truck with his own visual perception.